Field of the Invention
The disclosure relates to an image forming apparatus such as a copier and a printer and a feeding device used in the apparatus and executing a feed control over a recording material therein.
Description of the Related Art
Conventionally, an image forming apparatus such as a copier and a printer has a cassette configured to accommodate recording materials. The cassette has a regulating plate. The regulating plate may be positionally moved in accordance with the size of recording materials to regulate a movement of the recording materials accommodated in the cassette.
According to Japanese Patent Laid-Open No. 2015-105175, a time period from start of feeding of a recording material to detection of the recording material by a registration sensor is measured so that whether the position of a rear-end regulating plate is deviated from a proper position (or position depending on the size) or not based on the measured time period. The rear-end regulating plate here is a regulating plate configured to regulate rear ends (upstream ends in a feeding direction) of recording materials. If it is detected that the position of the rear-end regulating plate is deviated, a user may be prompted to check the cassette, which can reduce the possibility that a conveyance failure due to a delay of feeding of a recording material will occur in future. In a case where a conveyance failure actually occurs, a cause of the failure may be notified to a user so that the same type of conveyance failure can be prevented for improved usability.
On the other hand, it is known that an influence of friction with a previously fed recording material may result in varied positions of leading ends (downstream ends in the feeding direction) of recording materials accommodated in the cassette. According to International Publication No. WO2011/007406, in order to make leading ends of recording materials to be uniform, a control is executed in which a subsequent recording material is fed in advance until the leading end of the subsequent recording material reaches a separation nip formed by a feed roller and a retard roller. Performing such an operation for making positions of leading ends of recording materials uniform can reduce varied positions of the leading ends of the recording materials.
According to Japanese Patent Laid-Open No. 2015-105175, a longer time period may be required from start of feeding of a recording material to detection of the recording material by a registration sensor in a state that the position of the rear-end regulating plate is deviated, compared with a state that the position of the rear-end regulating plate is not deviated. However, execution of the control according to International Publication No. WO2011/007406 can adjust the position of the leading end of a subsequent recording material to match with the separation nip. Thus, even in a state that the position of the rear-end regulating plate is deviated, the measured time period is substantially equal to the measured time period in a state that the position of the rear-end regulating plate is not deviated. In other words, it is difficult to detect a deviation of the rear-end regulating plate.